Electrical appliance fire extinguisher

ABSTRACT

A fire extinguishing system for an electrical appliance, such as a television receiver, in which a generally-tubular container, filled with a synergistic mixture of an alkali metal or alkaline earth metal carbonate or bicarbonate and a synthetic metal silicate, is mounted in the cabinet, a dispersing means is mounted on one or both ends of the container, a propellant means, preferably including a gas impervious piston, a container of a pressurized gas and a spring-loaded puncturing means, is mounted in the container and a flame-actuated ignition means, preferably composed of specific amounts of platinum or palladium in intimate contact with aluminum or magnesium, is operatively attached to the propellant means and disposed about the interior of the cabinet. The ignition means may also be connected in the circuit of the appliance in a manner to shut off the appliance when the ignition means burns.

United States Patent Dunn 1 1 June 17, 1975 ELECTRICAL APPLIANCE FIRE EXTINGUISHER Primary E.\'aminerLloyd L. King Assistant Examiner-Michael Mar [76] lnvemor' 56 2225 3 Orchld Attorney, Agent, or Firm-Charles F. Steininger [22] Filed: Nov. 19, 1973 ABSTRACT Appl. No.: 416,870

Related US. Application Data Continuation-in-part of Ser, Nos. 131,333, April 5,

1971, Pat. No. 3,773,111, and Ser. No. 400,623,

Sept. 25, 1973, and Ser. No. 400,640, Sept. 25, 1973.

A fire extinguishing system for an electrical appliance, such as a television receiver, in which a generallytubular container, filled with a synergistic mixture of an alkali metal or alkaline earth metal carbonate or bicarbonate and a synthetic metal silicate, is mounted in the cabinet, 21 dispersing means is mounted on one or both ends of the container, a propellant means, preferably including a gas impervious piston, a container of a pressurized gas and a spring-loaded puncturing means, is mounted in the container and a flameactuated ignition means, preferably composed of specific amounts of platinum or palladium in intimate contact with aluminum or magnesium, is operatively attached to the propellant means and disposed about the interior of the cabinet. The ignition means may also be connected in the circuit of the appliance in a manner to shut off the appliance when the ignition means burns.

11 Claims, 7 Drawing Figures ELECTRICAL APPLIANCE FIRE EXTINGUISHER REFERENCES TO RELATED APPLICATIONS The present application is a continuation-in-part of applications Ser. No. 131,333, filed Apr. 5, 1971 now US. Pat. No. 3,773,111; Ser. No. 400,623, filed Sept. 25, 1973 and Ser. No. 400,640, filed Sept. 25, 1973, all by the present inventor. These prior applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION The present invention relates to a system for automatically sensing and extinguishing fires in electrical appliances housed in a cabinet or case. More specifically, the present invention relates to a system for automatically sensing and extinguishing fires in a television receiver.

There are any number of electrical appliances in the home and other locations which present a fire hazard. A number of such electrical appliances and devices are particularly dangerous since they generate substantial heat in their operation. If such appliances are enclosed by a case or cabinet, it is then necessary to provide air holes in the back covering or other portions of the case or cabinet in order to help dissipate the heat and provide'air circulation. Unfortunately, in providing for the dissipation of heat in this manner, the appliance is subject to collection of lint and dust within the casing or cabinet and on the electrical parts. This, obviously, adds to the fire hazard involved.

Chief among the electrical appliances, of the type referred to above, which are definite fire hazards are television receivers. National statistics indicate that a te1evision receiver is a major cause of fires in recent years, particularly due to their widespread use. Since a television receiver is usually the last electrical appliance to be turned off before a family retires, many costly and deadly fires have occurred from this source. This problem is further aggravated by the fact that static electrical arcs from high voltage often occur after a television receiver has been turned off. Consequently, residential fire alarms are being sold in tremendously increasing numbers on the basis that a television receiver is the most deadly appliance in the home even when turned off.

Such fire alarms are generally of one of two types. The first is a heat-actuated device which is usually automatically actuated at a temperature of approximately 135F. Among other things, such detectors have the distinct disadvantage that they cannot be utilized close to any device or appliance or in any room where considerable heat is generated. Otherwise, false alarms frequently occur. For example, they cannot be used in the kitchen in most cases and they cannot be used adjacent furnaces, heaters or appliances which generate heat. The second type of detector is an ionic smoke detector. Here again, there is always the possibility of numerous false alarms and it is difficult to locate such detectors without the occurance of false alarms while still having a detector adjacent the most common items or appliances which are fire hazards. Consequently, either type of conventional fire alarm is generally placed on the wall of a room about 6 to 8 inches from the ceiling. The obvious disadvantages of this are quite clear. By the time one of these detectors is actuated by heat or smoke, a major confiagration will be in progress or, at

the very least, an appliance, such as a television receiver, has been damaged beyond repair. In addition, such an alarm is only an alarm and there must be time for an individual to either extinguish the fire with a conventional fire extinguisher or call the fire department. The disastrous consequences of such delays are obvious.

It is therefore an object of the present invention to provide a system for the detection and extinguishment of incipient fires in appliances which normally generate heat and are generally enclosed in a casing or cabinet. It is a further object of the present invention to provide a system for the detection and extinguishment of fires in a television receiver. Another and further object of the present invention is to provide a system for detecting and extinguishing incipient fires in a television receiver before any consequent damage to the receiver itself. Still another object of the present invention is to provide a system for the detection and extinguishment of incipient fires in a television receiver which will preceed by a substantial factor the actuation of an ionic smoke detector or heat sensor fire alarm. A further object of the present invention is to provide a system for the detection and extinguishment of incipient fires in a television receiver wherein the detection and extinguishment equipment are located inside the television cabinet. Another and further object of the present invention is to provide a system for the detection and extinguishment of incipient fires in a television receiver wherein a flame within the receiver is detected and automatically extinguished in a matter of seconds, thereby preventing fiame propagation and ignition of surrounding walls, drapes and other fiammables common to residential furnishings and construction.

SUMMARY OF THE INVENTION Accordingly, the present invention provides in an appliance having a cabinet or casing surrounding its working parts, a container adapted to hold a supply of fire extinguishing agent, nozzle means on said container adapted to direct a spray of extinguishing agent over the entire working parts of the appliance, pressure means for applying pressure to the extinguishing agent and a flame-actuated sensor means disposed around and about the interior of the appliance which is resistant to ignition by heat but ignitable by a flame and adapted to actuate the pressure means. The sensor means may also extend into a power fuse mounted in the power circuit of the appliance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 of the drawings is a perspective view, in phantom, of a television receiver with the fire extinguishing system of the present invention installed therein:

FIG. 2 is an exploded view of the cannister assembly and nozzle assembly of the system of FIG. 1;

FIG. 3 is a cross-sectional view of the assembled nozzle assembly;

FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 3;

FIG. 5 is a side view of the actuator assembly and pressure means;

FIG. 6 is a top view of the actuator assembly and pressure means of FIG. 5; and

FIG. 7 is a modified form of the cannister assembly of FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 shows, in phantom, a television receiver 10. As is conventional, the receiver comprises a cabinet 12 housing the picture tube 14 and a conventional electrical chassis 16. Mounted on an interior wall is a fire extinguisher 18 comprising a cannister 20 adapted to contain a fire extinguishing agent and means for expelling the same and a nozzle assembly 22 adapted to distribute the extinguishing agent throughout the interior of the receiver 10. A single extinguisher 18 may be mounted inside the cabinet as shown in the Figure and the extinguishing agent will be distributed throughout the interior of the cabinet by direct dispersion and rebound from the walls, etc. of the interior of the receiver. Leading from the end of the extinguisher 18 is a sensor or ignition wire 24. Sensor or ignition wire 24 is disposed around and about the interior of the cabinet. In the present case, it is shown as disposed about the exterior of the picture tube through eyelets or hooks 26 mounted in the cabinet itself. The sensor wire 24 may also extend to a power cut-off means, such as a fuse 28 mounted in the power circuit of the receiver. As will be pointed out in greater detail hereinafter, the particular sensor or ignition wire utilized in the present invention is quite suited to act as the fuse element of a conventional fuse. Therefore, the wire 24 can be extended through the fuse itself and act as the fuse element to cut off the power when the wire 24 is ignited and burns.

FIG. 2 of the drawings shows an exploded view of the cannister assembly 20 and the nozzle assembly 22 of the fire extinguishing system of the present application. In FIG. 2, a main tubular body portion 24 is provided. Body portion 24 is threaded at its rear end portion 26. Mounted inside tubular body 24, adjacent the front end thereof and resting against a reduced shoulder therein, is frangible disc 28. The tubular body 24 is packed with a dry chemical fire extinguishing agent 30 (hereinafter referred to in greater detail). Thereafter, a piston 32 is positioned in tubular body 24. The rear end of tubular body portion 24 is then closed by means of frangible disc 34 mounted on actuator plate 36. Actuator plate 36 has mounted thereon actuator assembly 38. Actuator plate 36 rests on a shoulder (not shown) in end cap 40. Cap 40 is screwed on portion 26 of tubular body 24 and sealed by means of O-ring 42. A sensor wire 43 leads from the actuator assembly 38 through cap 40. The front end of tubular body 24 is closed by an integrally-formed, deflector head portion 44. Head portion 44 directs the extinguishing material 30 downwardly where it exits through mounting head 46. Mounted within an annular groove in mounting head 46 is O-ring 48 which forms a part of nozzle assembly 22. Nozzle assembly 22 includes nozzle base 50 which mounts on mounting head 46. Nozzle base 50 has hemispherical nozzle supports 52 provided with angularly-disposed apertures 54. Passing through apertures 54 are distributing nozzles 56. Nozzle base 50 and head 46 form a bayonet connection. Distributing nozzles 56 have mounted in their upper ends nozzle deflectors 58 and in their lower ends temporary nozzle seals 60. The free ends of distributing nozzles 56, which pass through apertures 54, have slidably mounted on the outside thereof nozzle retainers 62. Nozzle retainers 62 are press-fit on nozzles 56 in a manner such that nozzles 56 and nozzle retainers 62 are freely movable over a wide angular range about hemispherical supports 52.

FIGS. 3 and 4 of the drawings shown the nozzle assembly 22 (FIG. 2) in its assembled condition. The as sembly, of course, includes nozzle base having hemispherical projections 52 with apertures 54 formed therein. Passing into and through the apertures 54 is distributing nozzle 56. Distributing nozzle 56 has temporary end cap mounted in one end thereof and nozzle deflector 58 mounted in the opposite end. Distributing nozzle 56 is also provided at its upper end with angularly disposed apertures 64. When pressure is applied to the dry extinguishing agent 30 (FIG. 2) in body 24 of the cannister assembly, the pressurized extinguishing powder is forced outwardly through apertures 64 and the interior of nozzle 56 and this pressure blows cap 60 out the end of nozzle 56. Otherwise, cap 60 provides a seal to prevent grease moisture and the like from entering the nozzle assembly. Apertures 64 also serve a very distinct purpose. As will be seen from FIGS. 3 and 4, apertures 64 are disposed parallel to the radii of nozzle 56 and offset therefrom. By this placement, the powdered fire extinguishing agent exits through nozzle 56 in a swirling or a vortical motion due to the coaction of and placement of the apertures 64 with respect to deflector 58. This has a critical effect on the distribution of the powdered extinguishing agent over the area to be protected.

FIGS. 5 and 6 show the actuator assembly 38 in detail. Actuator assembly 38 is held in place by actuator bracket 66. Actuator bracket 66 is provided with a flange portion 68 which extends over and holds pressurized gas bottle 70 in place. Actuator bracket 66 is provided with apertures 72 which fit on posts of actuator plate 36. Passing through a central aperture between the posts is a screw 74 which passes into an aperture in plate 36 to hold actuator bracket 66 in place. Actuator bracket 66 is provided with an aperture 76 to receive pivot pin 78 of the actuator assembly. Mounted on pivot pin 78 is hammer bracket 80. Hammer bracket 80 carries hammer 82 with puncturing pin 84. The puncturing pin 84 is so aligned that it will puncture the seal of gas bottle 70 at an appropriate time. Hammer 82 is manufactured as a separate entity from hammer bracket 80 and is attached thereto by swaging a central post 86. Pivot pin 78 also carries helical, power spring 88 which has one end thereof resting on top of hammer bracket 80 and the other end thereof resting against a post of support plate 36. The solid line outline of hammer bracket 80, hammer 82 and spring 88 shown the active or released position of these elements. Shown in dashed lines is the cocked or inactive position of hammer bracket 80, hammer 82 and spring 88. Hammer bracket 86 is held in the cocked position by means of clip 90. Clip 90 is held in place by having two side extensions thereof pass into aperture 92 in the actuator bracket 66 and an aperture in plate 36. Clip 90 is therefore free to rotate or pivot to a limited extent making it possible to align the clip with hammer bracket 80. However, bracket 80 is thereby held in the cocked position by gripping the same between the legs of clip 90 and then wrapping sensor 43 about the free ends of he clip. Thus, it is obvious that the actuator, once cocked, will operate as follows: The sensor 43 will burn, releasing the tension on clip 90. Clip 90 will thereby release hammer bracket 80 which is driven by power spring 88. In the extreme, hammer bracket 80 will assume the position shown in solid lines with the hammer 82 against the end of gas bottle 70 and the puncturing pin 84 through the seal of gas bottle 70.

FIG. 7 shows a modified form of the cannister assembly of FIG. 2. The ends of the cannister assembly of FIG. 7 are mirror images of one another and all of the parts therein are designated with like numbers corresponding to the numbers of FIG. 2 except for the designations a and b to shown the different ends. The only basic difference between the cannister assembly of FIG. 7 and that of FIG. 2 is that a single actuator assembly 38 is mounted in the center of the casing and the casing is split into two identical sections 94 and 96. The actuator assembly 38 may be placed in a collar (not shown) which is threaded internally at both ends to accommodate the threaded portions of cannister sections 94 and 96. Nozzle assemblies, such as assembly 22 of FIG. 2, would be mounted on either end of sections 94 and 96. The construction such as that shown in FIG. 7 is quite convenient when mounted in an appliance such as a television receiver where the picture tuube passes through the center of the cabinet.

The cannister assembly and nozzle assembbly are preferably made of a material having a high degree of toughness, impact strength, heat resistance, dimensional stability and good electrical properties. While a number of materials can be utilized, the preferred ma terial is Lexan 101, manufactured by the General Electric Company.

The sensor or ignition wire should be selected on the basis of the conditions to which it is subjected. The primary requisite is that the sensor should not be spontaneously ignited by heat alone but will be ignited and burn rapidly when a flame strikes it. A desirable sensor wire is one having a minor proportion of a nobel metal, such as, platinum or palladium and a major proportion of aluminum or magnesium. A paticularly preferred material is a wire-type fuse known as PYROFUZE, manufactured by Pyrofuze Company of Mount Vernon, NY. This wire normally will not ignite or burn at radiant heat temperatures as high as l,200F but will ignite instantaneously and burn rapidly at a rate of about 09 foot per second when contacted by a flame.

The frangible discs are a laminate of paperpolyethylene-aluminum foilpolyethylene. They should have a rupturing strength of about pounds per square inch and a thickness of about 0.005 inch. The pressurized gas bottle is preferably a bottle containing liquified carbon dioxide. A suitable carbon dioxide cartridge is the type manufactured for Mae West life jackets. This component is designated by the US. Military as MIL-C-60lB, Type I.

The preferred fire extinguishing material for use in the present invention not only rapidly extinguishes the original flame but holds this condition and prevents or abates flashback or reignition even if the burner of the range is left on. This is detailed in copending Applications Ser. Nos. 400,623 and 400,640 and reference is made thereto. The fire extinguishing agent of the present invention is a synergistic mixture of about 50 to 95% by weight of an alkali metal carbonate, an alkaline earth metal carbonate, an alkali metal bicarbonte or an alkaline earth metal bicarbonate and about 50 to 5% by weight of a metal silicate. Because of its availability, effectiveness and freedom from toxicity, the preferred carbonate is sodium bicarbonate. Preferably, the sodium bicarbonte is present in amounts between about 85 and 60% by weight of the composition. Specifically, the most desirable composition contains about 78% to 80% by weight of sodium bicarbonate. The metal silicate is preferably a nontoxic alkali metal or alkaline earth metal silicate and of a substantially pure character, such as, a material manufactured by precipitation. A highly effective silicate for use in accordance with the present invention is Silene L, manufactured by Pittsburgh Plate Glass Company, Pittsburgh, Pennsylvania. This material is a precipitated calcium silicate and has an approximate analysis of CaO 19% and Si0 57%; and a loss on ignition of about 14%. It has a specific gravity of about 2.1 and bulk density of about 15 to 16 pounds per cubic foot. The preferred range of silicate is in the amount of 15 to 40% by weight and, specifically, the most effective has been found to be about 19% to 20% by weight. The composition may also include minor amounts of, up to about 5% by weight of conventional desiccants, lubricants, adsorbents and the like. Suitable materials of this character include calcium chloride, diatomaceous earth, silica gel, calcium stearate, etc. and preferably are present in an amount of about 3%. Calcium stearate is a preferred desiccant. However, this last component is not necessary to the synergistic effect of the mixture of the present invention nor to its free-flowing properties. It has been found in accordance with the present invention that the mixture of bicarbonate and silicate has free-flowing characteristics making its discharge from a suitable extinguishing apparatus superior to most conventional extinguishing agents. It also resists stratification in storage and in the extinguishing apparatus. The mixture is also capable of withstanding extreme temperatures without deterioration, thereby providing long shelf life and useful life without recharging or replacement and is relatively resistant to moisture deterioration. The dry, chemical fire extinguishing agent of the present invention is packed in body 24 of the cannister between frangible discs 28 and 34 by vibration of the cannister and is the only known dry, chemical extinghishing agent which can be loaded in this manner. This packing of the extinguishing agent has been approved by Underwriters Laboratories and, as indicated, is the only material approved for packing in this manner. This, of course, also contributes to non-stratification.

While specific examples and structures have been described and illustrated herein, it is to be understood that modifications thereof will be obvious to one skilled in the art. Accordingly, the present invention is to be limited only in accordance with the appended claims.

I claim:

1. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a generally-cylindrical container mounted in said cabinet, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means an including gas-impermeable piston means mounted adjacent said extinguishing agent and in gas-tight relation with the walls of said container and flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet.

2. A system in accordance with claim 1 wherein the propellant means includes a container of a gas under pressure and puncturing means for puncturing said container.

3. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a container mounted in said cabinet, a solid, powder-form fire extinguising agent disposed in said container, dispersing means operatively mounted on each end of said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguising agent through said distributing means, and flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet.

4. A fire extinguishing system for an electrical appliance, comprising, a container mounted adjacent said appliance, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent onto said appliance, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means and flame-responsive ignition means resistant to ignition by heat generated by said appliance, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure, operatively connected in an electrical circuit controlling said appliance to shut off said appliance when said ignition means burns and disposed adjacent said appliance in a position to be contacted by a flame should said appliance catch fire.

5. A system in accordance with claim 4 wherein a fuse means is operatively connected in an electrical circuit controlling the appliance and the ignition means is operatively connected to said fuse to blow said fuse when said ignition means burns.

6. A system in accordance with claim 4 wherein the ignition means also forms the fuse element of a fuse means and said fuse means is operatively mounted in an electrical circuit controlling the appliance.

7. A system in accordance with claim 4 wherein the ignition means is operatively connected to an electrical switch means and said switch means is mounted in an electrical circuit controlling the appliance to shut off said appliance when said ignition means burns.

8. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a container mounted in said cabinet, a solid, powder-form fire extinguishing agent disposed in said container comprising a metal carbonate selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, alkaline earth metal carbonates, alkaline earth metal bicarbonates and mixtures thereof, in a major amount of about 50 to 95% by weight, and a synthetic metal silicate, in a minor amount of about 50 to 5% by weight and sufficient to form an air-impermeable coating on the burning surface to which it is applied and prevent reignition of an extinguished flame for at least 10 minutes, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and flameresponsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet.

9. A system in accordance with claim 8 wherein the electrical appliance is a television receiver.

10. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a container mounted in said cabinet, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and wire-type, flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet and comprising 20 to by volume of a metal selected from the group consisting of platinum and palladium and 80 to 20% by volume of a metal selected from the group consisting of aluminum and magnesium.

11. A system in accordance with claim 10 wherein the electrical appliance is a television receiver. 

1. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a generally-cylindrical container mounted in said cabinet, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means an including gas-impermeable piston means mounted adjacent said extinguishing agent and in gas-tight relation with the walls of said container and flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet.
 2. A system in accordance with claim 1 wherein the propellant means includes a container of a gas under pressure and puncturing means for puncturing said container.
 3. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a container mounted in said cabinet, a solid, powder-form fire extinguising agent disposed in said container, dispersing means operatively mounted on each end of said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguising agent through said distributing means, and flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet.
 4. A fire extinguishing system for an electrical appliance, comprising, a container mounted adjacent said appliance, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent onto said appliance, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through saiD distributing means and flame-responsive ignition means resistant to ignition by heat generated by said appliance, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure, operatively connected in an electrical circuit controlling said appliance to shut off said appliance when said ignition means burns and disposed adjacent said appliance in a position to be contacted by a flame should said appliance catch fire.
 5. A system in accordance with claim 4 wherein a fuse means is operatively connected in an electrical circuit controlling the appliance and the ignition means is operatively connected to said fuse to blow said fuse when said ignition means burns.
 6. A system in accordance with claim 4 wherein the ignition means also forms the fuse element of a fuse means and said fuse means is operatively mounted in an electrical circuit controlling the appliance.
 7. A system in accordance with claim 4 wherein the ignition means is operatively connected to an electrical switch means and said switch means is mounted in an electrical circuit controlling the appliance to shut off said appliance when said ignition means burns.
 8. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a container mounted in said cabinet, a solid, powder-form fire extinguishing agent disposed in said container comprising a metal carbonate selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, alkaline earth metal carbonates, alkaline earth metal bicarbonates and mixtures thereof, in a major amount of about 50 to 95% by weight, and a synthetic metal silicate, in a minor amount of about 50 to 5% by weight and sufficient to form an air-impermeable coating on the burning surface to which it is applied and prevent reignition of an extinguished flame for at least 10 minutes, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet.
 9. A system in accordance with claim 8 wherein the electrical appliance is a television receiver.
 10. A fire extinguishing system for an electrical appliance having a cabinet surrounding its working parts, comprising, a container mounted in said cabinet, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and wire-type, flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet and comprising 20 to 80% by volume of a metal selected from the group consisting of platinum and palladium and 80 to 20% by volume of a metal selected from the group consisting of aluminum and magnesium.
 11. A system in accordance with claim 10 wherein the electrical appliance is a television receiver. 